It is a shameful that a woman has been illegally detained for five years in a "squalid" cell in HMP Bronzefield (Report, 22 August). The 2007 Corston report on women in prison legitimately argued that the vast majority of women did not need the physical security provided by the masculine model of prison regimes but required "relational security", a term coined by Wish (Women in Secure Hospitals, of which I was formerly a regional director), based on its years of advocacy work with women both detained in prison and forensic psychiatric hospitals. With the knowledge and training developed by Wish, which has been available to staff working in these services for the past 10 years, there is no excuse for any woman to be abused in this horrendous way. One has to ask what the independent monitoring board – whose role is to ensure that humane treatment of any "prisoner" is upheld and their human rights are not compromised – was doing. Laila NamdarkhanAbbots Langley, Herts

• The independent monitoring board at HMP Bronzefield should have known about the situation and challenged the authorities repeatedly, up to and including the minister of justice. At its best, the IMB is a most effective organisation for ensuring that prisons are operated in a truly humane manner. But an IMB is only truly effective if it is a high-quality team operating in a professional manner, understands its role and possesses the drive and character to carry it out.The work of the IMB as a whole is, unfortunately, weakened by the lack of an effective system to monitor, assess and advise its individual prison IMBs. If poorly organised, staffed and led, they become little more than a fig leaf to cover weaknesses in the prison system.Ken Ellis(ex-chairman of a prison IMB)Dereham, Norfolk

• This column was amended on 27 August 2013. "Causton" slipped into a reference to the Corston report.